Now we head to south africa and a new twist in the case of oscar pistorius, facing murder charges in the death of his girlfriend. Tonight we are learning about another chapter in his past, another allegation. Abc's amy robach tells us this news about the olympic star. Reporter: Today in south africa, oscar pistorius's lawyers are trying to reach a settlement with another woman who accused him of assault in 2009 and called the police. Pistorius sued her because he said it ruined his reputation and caused him to lose endorsement deals. Even though no assault charges were ever filed. Until two weeks ago, it seemed oscar pistorius could do no wrong. Because it's such a compelling, heart-warming story of a young man putting those carbon fiber blades on. There were millions of people with disabilities around the world cheering for him. Reporter: An icon on a ped stol, at least on the track. We don't know oscar pistorius. Wr what we're finding out is surprising. He's living a fast life, fast cars, dirt bikes, pet tigers and a passion for weapons. One of the things he would do, I'm amped, let's go to the shooting range. I thought it was bizarre then and in the light of day, even more bizarre now. Modern south africa is no post apartheid utopia, it's a very dangerous place. Every single house, barbed wire. Reporter: Last year after a series of jealous texts over an 18-year-old girlfriend, police say pistorius told another man he would break his legs. I was amazed. I was taken aback. I didn't think oscar had it in him to make those kinds of threats. And amy robach is here now. Tonight on "20/20," you're going to study the crime scene. That's right. We built a set and to skil that shows oscar pistorius's bathroom and bedroom. We're exploring two versions of what happened that night -- oscar's version and the prosecution's version. We'll talk about the little details, likewo cellphones found in the bathroom? And which side of the bed he slept on that night could make or break the case. I know you'll be taking us through tonight, a full hour of reporting from amy on "20/20," the fast times of oscar pistorius at 10:00 a.M. Eastern.

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